Device for indicating leaks in insulation of electric conductors.



Patented Sept. I0, I90L I. KITSIiI-I.v DEVICE FOR INDICATING LEAKS IN INSULATION 0F ELECTRIC CUNDUCTUHS.

(Application fled Jan. 24, 1900.)

(No Model.)

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A UNITED STATES PATENT EErcE.

DEVICE FOR INDICAIING LEAKS IN INSULATION 0F ELECTRIC CONDUCIORS.

SPECIFICATION forming part of' Letters Patent No. 682,204, dated September 10, 1901.

Application tiled January 24, 1900. Serial No. 2,651. (No model.)

To all whom t may concern,.-

Be it known that I, IsIDoR KrTsEE, of the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Devices for Indicating Leaks in the Insulation of Electric Conductors, of which the following is aspecitication.

My invention relates to an improvement in electric circuits.

The object of my invention is to provide means whereby defects in the circuit may easily be detected.

It frequently happens that the wiring in dwellings and stores becomes defective. In most cases theinsulation breaks down in time, and through the escape of the current fre- Often the conductor itself becomes heated either through a greater flow of current or through the change of molecules, whereby the brittleness of the conductor increases, and this again in time maylead to accidents. In short, conflagrations due to electric wires in dwellings as well as stores are not a very infrequent occurrence, and it would be of the utmost importance to detect any defects in the insulation of the circuit before the danger-point is reached.

The aim of my invention is to provide means for such protection.

Referring to the drawings, Figure l is a diagrammatical view wherein two separate cables are used.` Fig. 2 is a diagrammatical view wherein both wires are in one cable.

In Fig. l, A A' are the two main wires, and B B the insulation surrounding said wires. C C' are conducting-wrappings surrounding said insulation. D D' are outside insulations. E is an -electric bell, being electrically connected to C and A', respectively. E' is a second electric bell connected to A and C', respectively. F F F are lamps.

In Fig. 2, A A' are the two main wires. Gr is the insulation interposed between and surrounding said wires. I-I is aconducting-tube inclosing the wires with their insulation. E is an electric bell connected,with the interposition of the switch S, to the wire A' and the conducting-tube II, respectively. E' is a second electric bell connected, with the interposition of the switch S', to the wire A and the conductingenvelop H, respectively. F F are lamps.

I will first describe myinvention as applied to a circuit as illustrated in Fig. l. In this circuit every wire is carried separately into and throughout the building. Each of the circuit-wires is, as illustrated in the drawings, provided with the insulated conducting center core, the conductingwrapping, and the outer insulator. The wire proper may be provided with any of the insulation as now used. The conductingwrapping is preferably in the shape of a thin metallic bandsuch, for instance, as tin-foiL-which may be wrapped in the manner, as shown in the drawings, around the wire insulation, but instead of the spiral wrapping a conductingtube may be used. The mode of providing this conducting-wrapping with an outer insulator' may vary according to requirements. The circuit is provided with my safeguarding device in the following manner: The wire A of the circuit is connected with the 4 conducting-wrapping C' of the wire A', with the interposition of the alarm or calling-up device E', and the wire A' is connected, with the interposition of the alarm or calling-up device E, with the conducting-wrapping C of the wire A. If now through the overheating of the wire A the insulation of said wire becomes heated and therefore partially conducting, a slight flow of the current from that wire toward the conducting-wrapping willbe the result. A current-path will therefore be established between A and O', actuating the alarm or calling-up device E'. If wire A' is raised to a higher temperature, then a leakage will be established between A' and its conducting-wrapping, and therefore a current will iiow through the alarm or callingup device E. If from any cause whatsoever a leakage occurs between the ground and any of the circuitwires and the conducting-wrapping C or C' is connected to the ground or no outside insulation is applied to the conducting-wrapping, then the conducting-wrapping will at once be electrically connected with the circuit-wire and the alarm will come into play. In practice I prefer to make the electromagnet actuating the alarm IOO or calling-up device of a comparatively high resistance. I would suggest that in a onehundred-and-tenvolt circuit the resistance should not be less than five thousand ohms. This will serve two purposes-first, the current-flow would be very small, and, second,

.on account of the high resistance of the electromagnet it would be more capable of dctecting slight leakages.

The arrangement as shown in Fig. l is preferred in such places Where the current is provided from a central station using a three- Wire system, with the neutral wire grounded. The arrangement as shown -in Fig. 2 is preferred in isolated plants where the generator is perfectly insulated from the ground; but the arrangement as shown in Fig. 2 may be varied by providing the conducting-tube with an outer layer of insulating material.

I have illustrated the alarm devices E E as consisting of asimple bell; but other alarm devices may be placed in the circuit or the electromagnetic device may be provided with means to close a local circuit, thereby actuating one of the well-known calling-up or annunciating devices. Such arrangement is so well understood that it is unnecessary for me to describe or illustrate the same.

In Fig. 2 it is necessary to provide the alarm-circuit with a cut-outor switch for the reason that were both circuits normally closed a path for the current would be established even if the insulation is not defective. The modus operandi of ascertaining any defect in insulation or circuit in this figure is as follows: Normally both switches S and S are open. Vhenthe person in charge desires to ascertain if the circuit is in order, he first closes one of these two switches-say switch S-Whereby the alarm device E would come into play if the insulation of the wire A is defective. He then opens switch S and closes switch S', whereby the alarm device E would come into play if the insulation of the wire A is defective. He then closes both switches S S and establishes a circuit of high resistance from A through switch S', alarm device Ef, outer conducting-wrapping, alarm device E, switch S, and wire A. If now the insulation between the two Wires A and A is defective, then the sound of the alarm device will be weaker in inverse proportion to the strength of the resistance between the two wires and may cease entirely if the insulation is broken down.

Instead of an alarm any of the well-known indicating devices may be used.

Thus my invention and the means of carrying out my invention are in contradistinction to the aims and means employed in the socalled tire-alarm systems. In this system one or the other of the conductors has to be of an easily-fusible metal, for the reason that electric contact may be made in the circuit, or, if the circuit is a continuous one, the electric contact may be broken. In all these cases t-he fusing of the conductor is necessary, so as to alter the electrical condition of the circuit and to actuate the fire-alarm devices. In my invention the fusing of the circuitwire or independent conductor is not contemplated, but, on the contrary, both the circuit,as wellas independent conductor, should be of a metal capable of withstanding a high temperature, and it is only the greater or lesser resistance of the insulating material` which determines the status of the indicating devices, and whereas the tire-alarm circuits do not carry any current except the slight current necessary to actuate the alarm device my invention is only applicable to such circuits carrying normally a current sufficient to feed consuming devices placed either in se ries or multiple arc in this circuit, and the annunciating devices embodying my invention are adapted to be actuated by slight traces of such current if following apath not contemplated.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is-Y 1. In combination, a circuit carryinga current useful for light or power, consuming de-v vices placed in said circuit, and an indicating device, one terminal of which is connected to the circuit propel', and the second terminal of which is connected to a conductor insulated from, but in proximity to said circuit.

2. In a device to protect buildings from in-` jury due to the leakage of electric energy, a

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conductor or conductors carrying said elecrying circuit, and with the other terminal to the conducting-envelop.

3. A circuit, carrying an electric current, incandescent lamps connected in multiple arc as to said circuit, an insulating-envelop for each line-Wire of said circuit, and a conducting-envelop inclosing both of said line-wires, in combination with an indicating or alarm device connected to one of the wires of which said circuit is formed and to the conducting envelop, respectively.

4. Inan electric circuit forlight and power, two conducting-lines, each provided with an insulating-envelop, a conducting-envelop inclosing the insulating-envelop, consuming de vices connected to the conducting-lines, and an indicating device of a resistance higher than the resistance of any of the consuming' devices, connected to one of the 'linewires and the conducting-envelop respectively.

5. In combination with a current-carrying circuit, consuming devices placed in said circuit, an alarm device connected, with interposition of a switch, to the circuit and to IIO a metallic envelop surrounding said circuit, independent conductor, and means to open but insulated therefrom. and close the indicating-circuit.

G. A circuit carrying an electric current Intestiinony whereofI sign my naine,in the useful for light and power, insulating Inatepresence of two subscribing witnesses, this 5 rial surrounding the wire of said circuit, con- 22d day of January, 1900.

ducting material in Contact with said insur lating material, consuming devices for said ISIDOR KIrSE-E circuit, and a high-resistance-indicating de- Witnesses:

vice connecting With one terminal to the con- WVM. M. DEUTSCH, 1o ducting-circuit, andwitll one terminal to the EDITH I. STILLEY. 

